• Journal of Ecology and Environment
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• 제38권4호
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• pp.517-528
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• 2015

Litter decomposition is an important process in terrestrial ecosystem. However, studies on decomposition are rare, especially in evergreen broadleaf trees. We collected the leaf litter of five evergreen broadleaf trees (Daphniphyllum macropodum, Dendropanax morbifera, Castanopsis cuspidata var. thunbergii, Machilus thunbergii and Quercus acuta), and carried out a decomposition experiment using the litterbag method in Ju-do, Wando-gun, Korea for 731 days from December 25, 2011 to December 25, 2013. Among the five experimental tree species, C. cuspidata var. thunbergii distribution was limited in Jeju Island, and D. macropodum was distributed at the highest latitude at Mt. Baekyang (N 35°40′). About 2% of the initial litter mass of D. macropodum and D. morbifera remained, while 20.9% remained for C. cuspidata var. thunbergii, 30.4% for M. thunbergii, and 31.6% for Q. acuta. D. macropodum litter decayed four times faster (k = 2.02 yr^-1) than the litter of Q. acuta (k = 0.58 yr^-1). The decomposition of litter was positively influenced by thermal climate such as accumulated mean daily air temperature (year day index) and precipitation, as well as by physical characteristics such as thickness (R²=0.939, P = 0.007) and specific leaf area (SLA) (R² = 0.964, P = 0.003). The characteristics of chemical composition such as lignin (R² = 0.939, P = 0.007) and water-soluble materials (R² = 0.898, P = 0.014) showed significant correlations with litter decomposition. However, the nutrients in litter showed complicated species-specific trends. The litter of D. macropodum and D. morbifera had fast decomposition despite their low nitrogen concentration and high C/N ratio. This means that the litter decomposition was more strongly affected by physical characteristics than chemical composition and nutrient content. On the other hand, the litter of Q. acuta which had the slowest decay rate had a high amount of N and low C/N ratio. Thus, the decomposition of Q. acuta litter was more affected by the P content of the litter than the N content, although all litter had similar physical characteristics.

• 한국환경과학회지
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• 제13권9호
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• pp.747-757
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• 2004

The objectives of this study were to investigate the physical, chemical, and structural characteristics of the stream, especially Mugeo and Yeochon which are being changed to ecological stream by Ulsan city, and to acquire the considerations such as the planning element and plan criteria of the streams for making ecological stream system. Water quality, water quantity, vegetation, in stream structures and facilities, and land usage of the streams were investigated and the build up capabilities of ecological stream for the two streams were also analyzed. Planning elements for restoration to ecological stream included physical and biological purification methods in water quality, short term water acquire alternatives in water quantity, and vegetation recovery plan and improvement of habitation environment in ecological system, respectively. Planing elements in physical structures and facilities also included recovery of concrete levee and removal and recovery of covered channel.

• 공업화학
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• 제10권3호
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• pp.354-361
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• 1999

티타늄을 물리증착시킨 후 열처리한 막과 플라즈마에 의해 무정형 실리콘을 증착시킨 후 열처리한 막은 양질의 결정성을 갖는 Si가 풍부한 티타늄 실리사이드가 형성되고, 열처리 과정에서 에피택시 성장을 위한 격자들의 회전에 의해 다양한 형태의 격자구조를 갖는다. 티타늄 실리사이드 막의 band gap은 플라즈마에 의해 a-Si:H막을 증착시킨 후 열처리한 막이 수소의 탈착에 의해 제공된 dangling bond, a-Si 등의 영향을 받아 1.14~1.165 eV의 값을 가진다. 물리증착하여 열처리한 막의 Urbach tail인 $E_0$는 0.045~0.05 eV 범위로 거의 일정하고, 플라즈마에 의해 a-Si:H 막을 증착시킨 후 열처리한 막의 결함수는 Ti/Si를 열처리했을 때 얻어진 결함수보다 약 2~3 배 정도 많은 것으로 나타났다.

• 한국응용과학기술학회지
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• 제28권4호
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• pp.508-516
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• 2011

Hydrotreated biodiesel(HBD) is paraffinic bio-based liquid, with the chemical structure $C_nH_{2n+2}$, originating from vegetable oil(the process can also be applied to animal fat). The oil or fat is treated in a number of process, the most important being hydrogenation, in order to create a bio-based liquid diesel fuel. During the hydrogenation, oxygen is removed from the triglyceride and converted into water. Propane is formed as a by product and can be combusted and used for energy production. HBD can be used in conventional diesel engines, pure or blended with conventional diesel, due to its similar physical properties to diesel. This study reports the quality characteristics with chemical and physical properties as an alternative diesel fuel. Especially, HBD showed higher cetane value and number than FAME, and it is consisted of $C_{15}$ - $C_{18}$ n-paraffinic compounds. We also describes quality characteristics of HBD blends(2, 5, 10, 20, 30, 40, 50 vol%) in automotive diesel. HBD blends(max. 20 vol%) were the limit by the Korean specification due to poor low temperature characteristics.

• 펄프종이기술
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• 제30권3호
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• pp.15-21
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• 1998

Crude enzymes of Trichoderma viride and Phanerochaete chrysosporium were evaluated for their effect to brightness and physical properties of recycled pulp from newspaper and corrugated container board. The brightness of recycled pulp from newspaper increased with crude enzymes from Trichoderma viride and Phanerochaete chrysosporium. The brightness of recycled pulp of corrugated container board increased with crude enzyme from Phanerochaete chrysosporium, but decreased with crude enzyme from Trichoderma viride. The Δbrightness with chemical bleaching of crude enzyme treated pulp was lower than that of heat killed enzyme treated pulp, but the final brightness of pulp was increased. Modification of recycled paper with crude enzymes can result in a substantial increase in physical properties with little no loss in pulp freeness.

• 한국응용과학기술학회지
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• 제40권5호
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• pp.945-954
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• 2023

In this study, Sparassis crispa(cauliflower mushroom), which is rich in beta-glucan, was pulverized using ultrafine grinding technology for its potential utilization as a diverse food ingredient. The physical and antioxidant properties of cauliflower mushroom powder were evaluated at various grinding times. The results showed that as the grinding time of cauliflower mushroom increased, the average particle size significantly decreased (p<0.05). Additionally, the water-holding capacity, swelling capacity, and water solubility index of cauliflower mushroom increased significantly(p<0.05). Based on the analysis mentioned above, cauliflower mushroom prepared as a superfine powder for 5 minutes exhibited superior physical and chemical properties as well as antioxidant characteristics and is expected to be widely used in various foods.

• Journal of the Korean Wood Science and Technology
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• 제42권5호
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• pp.555-562
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• 2014

Characteristics of carbonized fiberboard such as chemical materials absorption, electromagnetic shielding, and electrical and mechanical performance were determined in previous studies. The carbonized board therefore confirmed that having excellent abilities of these characteristics. In this study, the effect of density on physical properties and sound absorption properties of carbonized fiberboards at $800^{\circ}C$ were investigated for the potential use of carbonized fiberboards as a replacement of conventional sound absorbing material. The thickness of fiberboards after carbonization was reduced 49.9%, 40.7%, and 43.3% in low density fiberboard (LDF), medium density fiberboard (MDF), and high density fiberboard (HDF), respectively. Based on SEM images, porosity of carbonized fiberboard increased by carbonization due to removing adhesives. Moreover, carbonization did not destroy structure of wood fiber based on SEM results. Carbonization process influenced contraction of fiberboard. The sound absorption coefficient of carbonized low density fiberboard (c-LDF) was higher than those of carbonized medium density fiberboard (c-MDF) and carbonized high density fiberboard (c-HDF). This result was similar with original fiberboards, which indicated sound absorbing ability was not significantly changed by carbonization compared to that of original fiberboards. Therefore, the sound absorbing coefficient may depend on source, texture, and density of fiberboard rather than carbonization.

• 한국표면공학회지
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• 제43권2호
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• pp.64-72
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• 2010

CuSnZn electroplating was investigated as alternative to Ni plating. Evaluation of electrolyte and plating process was performed to control physical characteristics of the film, and to collect practical data for application. Hull-cell test was conducted for basic comparison of two commercialized products and developed product. Based on hull-cell test results, long term test of three electrolytes was performed. Various analysis on long term tested electrolyte and samples have been done. Reliable and practical data was collected using FE-SEM (FEI, Sirion), EDX (ThermoNoran SIX-200E), ICP Spectrometer (GBC Scientifi c, Integra XL), FIB (FEI, Nova600) for anlysis. Physical analysis and reliability test of the long term tested film were also carried out. Through this investigation plating time, plating speed, electrolyte composition, electrolyte metal consumption, hardness and corrosion resistance has been compared. This set of data is used to predict and control the chemical composition of the film and modify the physical characteristics of the CuSnZn alloy.

• 한국농공학회논문집
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• 제50권1호
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• pp.61-68
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• 2008

It is essential to analyze and classify the physical characteristics of weathered granite for engineering purposes. This paper is to suggest a physical method to determine the degree of weathering of weathered soils. A new classification method for determining the degree of weathering is suggested, based upon the results from laboratory tests including fall cone test. According to the proposed physical method using fall cone apparatus, the measured values of the samples from the same area show distinctive difference of weathering. The water content tends to increase with increasing the degree of weathering at the same penetration in fall cone test. And relationship between CWI and water content are expressed one equation in Hwaseong area and Ilsan area.

• 공업화학
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• 제30권1호
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• pp.54-61
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• 2019

본 연구에서는 Cu(II)의 흡착처리 후, 용액 내 함유된 폐흡착제의 효율적인 분리를 위하여 제올라이트(zeolite 4A)의 표면에 금속(Me = Co, Mn, Ni)이 치환된 페라이트 나노 입자를 성장시킨 자성흡착제를 합성하였다. 제올라이트 표면의 금속 페라이트는 용매열 합성법으로 제조되었으며, 자성흡착제의 특성은 XRD (X-ray diffractometer), SEM (scanning electron microscopy) 및 PPMS (physical property measurement system)로 분석하였다. Co-ferrite가 코팅된 제올라이트 복합체(CFZC)의 포화자화율이 5 emu/g으로 가장 높았으며, Cu(II)의 흡착 성능도 우수하였다. CFZC에 의한 Cu(II)의 흡착결과 값들은 298 K에서 Langmuir식에 잘 적용되었다. 그리고 Cu(II)의 흡착공정은 유사 2차 속도식에 부합하였다. 자유에너지 변화값(${\Delta}G^0=-4.63{\sim}-5.21kJ/mol$)은 Cu(II)의 흡착이 298~313 K 범위에서 자발적임을 나타내었다.